As the Fairmount Corridor Commuter Rail Line train peeled away from Readville one morning, a stocky conductor began collecting fares on the only car open to passengers. Scanning rows of empty seats, he realized, as is the case most midmornings, the task would be easy.

Since 2005, the Massachusetts Bay Transportation Authority has spent $200 million on massive improvements to the Fairmount line, which runs through Hyde Park, Dorchester, Mattapan, and Roxbury to South Station. The aim is to fulfill the state’s commitment to return rapid transit to sections of Boston’s less prosperous communities.

But as the T prepares to open two new stations on the 9.2 mile track next month, ridership remains dismally low.

The possible reasons: trains don’t run frequently, fares vary, the route does not fit some passengers’ needs, and bus-dependent commuters who had to make do without rapid transit service before are not ready to change their patterns and come on board.

“I think this is great, but it doesn’t go where I have to go,” said Shikora Ennis, a 27-year-old Dorchester resident who takes a series of buses and a trolley to get to work in Newton.

Operating entirely in Boston, the Fairmount commuter rail is trying hard to be a subway. It rumbles closely by the backyards of three-deckers in densely populated areas where merengue drifts from windows, pajamas flap on clothes lines, and buses grind through clogged streets.

‘We wanted to have the option of being able to get on a train the same as people in other communities.’

“This is a centerpiece in our communities,’’ said Mela Bush, an activist with Greater Four Corners Action Coalition, which pushed and got funding for rail service in that section of Dorchester. “It’s been a civil rights battle from day one.”

First opened as a Midland Railroad in 1855, the line was used for passenger service for 88 years, and later for freight. Passenger service ran again for a period in the 1970s when construction along the Southwest Corridor necessitated the rerouting of South Station-bound trains through Dorchester. But when the MBTA tried to revert the track to light freight, community advocates pushed back.

“We wanted to have the option of being able to get on a train the same as people in other communities,’’ Bush said. “We want to get on the train to get where we want to go at a price we can afford.’’

Improvements began in 2005 with the reconstruction of deficient bridges and upgrades to the Morton Street and Uphams Corner stations. Four new stations will be added, including one on Talbot Avenue that opened with little public notice last year and a proposed Blue Hill Avenue stop that is facing stiff resistance from residents. The Four Corners/Geneva station in Dorchester and the Newmarket stop near South Bay will soon open.

So much is riding on the line, the shortest commuter rail with the lowest weekday ridership of roughly 1,250. City, state, and neighborhood planners are hoping the new stations, rising like beacons of promise in low-income communities, will boost businesses, jobs, and development near the stops.

“We’ve got about 120,000 people there, and they are very diverse communities. These are culturally rich communities,’’ said Beverly Scott, MBTA general manager. “This is one of those corridors where there is absolutely no question about the opportunities [for] new development around these new stations. The potential is tremendous.”

But along Boston streets, some worry that an economic boon will drive up housing prices and them out of their neighborhoods, while others are skeptical that a commuter rail with scattered service — including no weekend or holiday service — will generate the kind of economic vitality that advocates want.

“They are doing this because of gentrification and white people moving into the city,’’ said a Mattapan resident who only identified himself as Gregory.

The Fairmount line is fraught with misunderstandings, controversy, and unfinished business. Advocates from the Fairmount Indigo Coalition slammed the MBTA for doing little to market it or educate the public about the value of the service. Many people here still associate the commuter rail with the suburbs.

Aiming to avoid “pitting one community against another,’’ advocates say they have had little success getting the T to make fares equitable on the line. A one-way ticket from Readville is $6, $5.50 at Hyde Park, and just $2 — the cost of a Charlie Card ticket — in Dorchester, Roxbury, and Mattapan. And the disparity is creating tensions.

Neighborhood advocates also blame the T for trimming service during the project’s construction and not returning it to the prior levels. And they want the T to cease the practice of only picking up passengers waiting on station platforms who are visible to the engineers.

“We just have to keep on fighting,’’ said Bush, whose group plans to conduct a survey and community forums to get more people on board. “We fought for the line, and we will keep fighting until the full vision is realized.”

T officials said they are working on possible fare adjustments on the line, but are focused on establishing equity and fairness overall. Scott is also in talks with community groups about how to best promote the line.

“That is going to be one of the biggest challenges for all of us,’’ Scott said. “This is going to take a major partnership, real marketing, communications, and education about the line.”

In parts of the city, it will be a hard sell. Joyce Quinerly
-Daniel, a 71-year-old Dorchester matriarch, keeps a list of grievances about the line, the most egregious of which was when construction crews at the Talbot Avenue station tore down her wooden privacy fence. Added to her horror, she said, was when she caught her granddaughter sitting on the bed in a back room one day and waving at a man on the T platform overlooking her yard.

The T is erecting a black privacy fence on either side of the station.

In Mattapan, opposition looms on Woodhaven Street, where residents have been fighting the T’s plan to build a station near their homes on Blue Hill Avenue. They want the stop relocated and said they are satisfied with buses that rumble close by.

“We feel it is redundant and unnecessary to spend millions of dollars to construct a station on Blue Hill Avenue,’’ said Mattapan resident Barbara Fields.

On the Fairmount line one morning, views were mixed among passengers on the 25-minute commute to South Station, where they will make connections to travel to their jobs at the airport, colleges, and offices north of Boston.

“It’s a great benefit to a lot us in this area who don’t have immediate access to get downtown,’’ said Terry Jones, a 35-year-old artist on his way from Talbot Avenue to his studio in Charlestown.

Okella Wood, a 30-year-old information technology technician, said he’s thankful to be off the buses. “The 22 and the 28 were just horrible ways to get to work. It’s crowded and its loud,’’ he said of two popular bus routes out of Ashmont Station and Mattapan Square. “One of the things I like about the commuter rail is that it’s quiet.”

Heading to his Uphams Corner neighborhood from South Station recently, Stephen Moss recalled when the elevated Orange line screeched through the heart of the minority community and the void that was created when it was taken down. “This doesn’t pick up the same areas, but it gets us to where we want to go quickly,’’ he said, pausing. “It’s not perfect.”